This invention relates generally to cleansing bars, and more particularly to cleansing bars having a plurality of layers of different materials oriented along a plane perpendicular to the plane formed by the x and y-axis of said bar.
Solid cleansing materials in the form of bars or cakes have been commercially available for many years. These bars may consist of soaps or detergents and may contain various other substances such as colouring materials, perfumes, benefiting agents, moisturisers and fillers. Different cleansing bar formulations are used to accomplish different cleansing needs. For example, skin on some parts of the body may be more sensitive than other areas. Some body areas are also more prone to perspire than other areas. In addition, the hands are more often exposed to more hard to remove dirt and grease than the rest of the body. These divergent cleansing problems have lead to the production of different cleansing bars designed for such different needs. Moreover, various individuals in the household may have different preferences or needs so that the household may keep on hand, at the lavatory or the shower, several different cleansing bars.
European Patent Application No. 366209 titled xe2x80x9cMethod of Production of Tablets of Toiletxe2x80x9d, published May 2, 1990, and U.S. Pat. No. 4,996,000 titled xe2x80x9cMulti-Layer Cleansing Barxe2x80x9d, issued to Dale R. Redeker on Feb. 26, 1999 both disclose a cast moulded cleansing bar having a plurality of layers of different cleansing materials oriented along a plane parallel to the plane formed by the x and y-axis.
As used herein, the x axis is positioned along the longest dimension of the bar, typically the length, the y axis is positioned along the 2nd longest dimension, typically the width, and the z axis is positioned along the shortest dimension of the bar, typically the height.
Bars having layers oriented along a plane parallel to the plane formed by the x and y-axis of the bar are characterised in that the user must rotate the bar in order to contact a substantial area of a different cleansing material. These bars are usually made using a layer by layer cast molding or an extrusion process. On the other hand, the user would not have to rotate the toilet bar in order to simultaneously contact substantial areas of different cleansing materials using the inventive toilet bar.
U.S. Pat. No. 5,198,140 titled xe2x80x9cDual Composition Toilet or Detergent Bar Containing Convoluted Surfaces and Tongue and Groove Interlockxe2x80x9d issued to David Joshi et al., on Mar. 30, 1993, discloses an extrusion formed dual composition bar, the two layers of which are oriented along a plane parallel to the plane formed by the x and y-axis of the bar of the bar. Japanese Patent Kokai Application No. 59-157200, published in Sep. 6, 1984, discloses a two phase toilet bar where the boundary layer is oriented along the bar""s plane perpendicular to the plane formed by the x and y-axis of the bar. This two phase is made by melting casting a first cleansing composition, removing the first casting from the mold, spraying with coloring pigment, cutting the casting to shape a decorative curve, repositioning the cut first casting in a mold, and casting a second cleansing composition, which adheres to the first cleansing composition layer, to form a two phase bar with a curvilinear boundary layer. Although the finished bar of JP 59-157200 may be produced in a reproducible fashion, this process is disadvantageous because of the many separate manufacturing steps required. U.S. Pat. No. 5,217,639 titled xe2x80x9cDual Phase Toilet Bar Containing a Clear Portion and an Opaque Portion Joined Along a Single Curvilinear Shaped Surfacexe2x80x9d issued to Nicolas Mottola on Jun. 8, 1993, discloses a dual phase toilet bar where the interface layer between the two phases of the bar is located generally along the plane parallel to the plane formed by the x and y-axis. The bar is cast by a sequential molding technique wherein a first molten toilet composition is poured into a plastic mold filing the mold to the 50% mark, allowed to harden, and then a second molten toilet composition is poured into the mold and subsequently allowed to harden. One disadvantage of this molding technique is the variability of the boundary line that is obtained between the two cleansing materials.
None of the foregoing patents however, disclose a toilet bar with multi-layers cast along a straight or curvilinear plane perpendicular to the plane formed by the x and y-axis of said bar, nor a molding process where a formed divider is used to control the shape of each layer reproducibly in a multi-layer toilet bar such that the shape of the boundary layer can be custom made and is consistent from bar to bar. A distinct drawback of bars that are cast without formed dividers is that they may display random variation with the position of the boundary between the different cleansing compositions.
In one aspect, the present invention relates to a multi-layer toilet bar containing a plurality of layers of cleansing material which are oriented to give maximum simultaneous benefit to the user of the toilet bar. In another aspect of the present invention, multi-layer toilet bars are provided with highly reproducible boundary lines between each layer. In another aspect of the present invention, a multi-layer toilet bar is provided that functions similarly to conventional toilet bar and its cleansing activity yet can provide skin benefits associated with different cleansing material compositions. A further aspect of the present invention is to provide a multi-layer toilet bar wherein certain active ingredients are incorporated into one layer but, not in the other. A still further aspect of the present invention is to provide a process for manufacturing a multi-layer toilet bar wherein a highly reproducible plurality of boundary layers oriented along the plane perpendicular to the plane formed by the x and y-axis of the bar is obtainable. These and other aspects of the present invention will become more apparent from the summary, detailed description, and examples which follow.
A multi-layer toilet bar is provided comprising a plurality of layers of cleansing materials, the layers having a common interface along said bar""s flat or curvilinear plane perpendicular to the plane formed by the x and y-axis of said bar and said layers having been melt cast in a unitary mold having a cavity and at least one removable formed divider contained within said cavity. The multi-layer bar is cast using a melt casting process that is continuous whereby the casting is not removed from the mold prior to completion of casting the finished toilet bar. Preferably, the multi-layer toilet bar has two layers of cleansing material and the mold has one removable formed divider. The formed divider can be slidably positioned in the mold cavity and in another aspect can be pivotally positioned in the mold cavity in a first position and the like. Preferably, the formed divider has a curvilinear shape.
Preferably one of the layers of the multi-layer toilet bar is composed of a cleansing material which lathers and another layer is composed of a cleansing material which moisturises the skin. A first melt casting process for making the multi-layer toilet bar is also provided which comprises the steps of: positioning at least one removable formed divider along a flat or curvilinear plane perpendicular to the plane formed by the x and y-axis of said bar in a unitary mold cavity to form at least two cavities; pouring a molten cleansing material into a first cavity defined by said mold and the removable divider; cooling the molten cleansing material until it is hardened sufficiently so that the formed divider can be removed from the mold; removing the divider from the mold either by sliding, pivoting or the like; pouring a second molten cleansing material into the mold cavity defined by the first hardened material and the mold; cooling the second molten cleansing material until it is hardened, and finally ejecting a hardened multi-layer toilet bar casting from the mold. Preferably, the process is continuous wherein the melt casting is not removed from the mold prior to completion of the casting of the finished bar. In another embodiment, a plurality of molten cleansing materials at a first temperature can be poured simultaneously or consecutively into their respective cavities, the molten material allowed to cool to a semi-solid state at a second temperature, and the removable dividers are then removed from the mold while at least one of the molten cleansing materials at said second temperature is hot enough to both flow away from the removable divider and fill the space in the mold formerly occupied by the divider. Preferably two molten materials are poured into two separate cavities divided by a single removable divider. In the case of the simultaneous pouring of a plurality of molten materials, the removable divider is preferably removed before the molten material cools to a second temperature of 85xc2x0 C. Preferably, only one removable divider is positioned in the mold cavity and made to be slidably removed from the mold or pivotally removed from the mold. Preferably the multi-cleansing material is cooled by a method selected from the group consisting of refrigeration, cryogenics, ambient air cooling, and the like. In another embodiment of the inventive bar and process, at least one of the removable formed dividers may be a water soluble or water dispersible solid material, preferably a solid cleansing material, which is not removed after casting the adjacent layers whereby the divider becomes part of the finished bar.